Different valve styles have been used downhole. One type is a sliding sleeve valve that can selectively cover or open holes in a casing or liner string. These valves are typically shifted with a shifting tool that grabs a recess in the sleeve and pulls or pushes the sleeve to open or close the wall ports in the tubular. Some examples are U.S. Pat. Nos. 5,549,161; 7,556,102 and 7,503,390.
Formation isolation valves have been used that have a ball that is attached to a sleeve so that movement of the sleeve results in ball rotation between open and closed position. These valves typically included a piston responsive to tubing pressure that worked in conjunction with a j-slot mechanism. The valve was closed mechanically but could be opened once with a predetermined number of pressure cycles on the piston. Eventually, a long slot in the j-slot would be reached to allow a spring or a compressed gas reservoir to move an operating sleeve into another sleeve that was attached to the ball so that the ball could be rotated to the open position. In one design the ball was locked after moving into the open position but that lock could be overcome with another tool run downhole. There was also a provision for an emergency opening with a pressure tool if for some reason the pressure cycles failed to open the ball. This design is illustrated in U.S. Pat. No. 7,210,534. Other formation isolation valves that came as an assembly of a mechanically operated ball that had the option of opening with pressure cycles until a j-slot allowed a pressurized chamber charged to a known specific pressure to move an operating sleeve against another sleeve to get the ball to turn open are illustrated in U.S. Pat. Nos. 5,810,087 and 6,230,807 while U.S. Pat. No. 5,950,733 initiates opening the ball with pressure that breaks a rupture disc to liberate pressure previously stored to move a sleeve to open that valve.
These combination valves with the hydraulic open feature bundled into a mechanical valve such as a ball valve are very expensive and in many applications represent overkill because a manually operated barrier valve such as with a shifting tool run in on coiled tubing, for example would be sufficient and within the budget for the particular project. On the other hand, the specification for some projects changes where the previously ordered manual barrier valve is determined to be insufficient for the application without a hydraulic opening feature. A hydraulically operated module of the present invention addresses this need for flexibility and further makes it possible for use of the module on a variety of tools when those tools can respond to shifting of an operating rod. The hydraulic module further incorporates either a onetime only configuration which is the simpler variation or another variation that can be re-cocked after an actuation with a tool run in from the surface to move the operating piston back up. The unique configuration of the cycling control assembly allows the ability to re-cock with minimal displacement of the operating rod so that the tool can be shorter because the operating rod does not need to be displaced after the valve opens any further than it takes to land a snap ring back in a groove so that the series of pressure cycles can resume when another hydraulic opening of the valve is required. The above system was described in detail in a commonly assigned application in the U.S. having Ser. No. 12/618,123 and filed on Nov. 13, 2009, entitled Modular Hydraulic Operator for a Subterranean Tool and whose contents are incorporated by reference herein as though fully set forth.
In another aspect, a backup potential energy source is provided that provides a force assist when trying to crack the valve open against high pressure differentials where an initial force to turn a ball toward open can be in the order of thousands of pounds of force. This auxiliary force is retained isolated during the predetermined pressure cycles that do not release the auxiliary force until the pressure is released on a predetermined cycle so that the boost force is initially applicable as the valve begins to open while the remainder of the movement is accomplished with the indexing spring. Variations that are one time operation or resettable with a tool are described.
These and other advantages of the present invention will become more apparent to those skilled in the art from a review of the description of the preferred embodiment and the associated drawings while recognizing that the full scope of the invention is given by the appended claims.